Shipping containers are used for transporting many different types of cargoes. Cargoes requiring temperature control and/or ventilation may require, for example, a refrigeration unit comprising a fan motor, condenser coils, liquid receive, compressor, contactor panel and a micro-computer controller coupled to the shipping container. Conventional shipping containers have housed such refrigeration units in the container's main frame. The main frame may be secured by huckbolts to an open end of the refrigeration unit and sealed with silicone.
A conventional main frame is shown in FIGS. 1 and 2. The profile of this main frame is first punched from sheet metal, then further profiled where necessary and then the profiled sheets are welded together to create the final main frame profile required for housing a refrigeration unit. Producing a main frame in this manner is expensive and time consuming.